2011_primeras Experiencias Control Sarna Pecan MISIONES

MAR DEL PLATA 2011

Asociacin Argentina de Fitopatlogos

2 Congreso Argentino De Fitopatologa Libro de Resmenes1, 2 y 3 de junio de 2011 Mar del Plata, Argentina

LIBRO de RESMENES

2 Congreso Argentino De Fitopatologa

1, 2 y 3 de junio de 2011 Mar del Plata, Buenos Aires - Argentina

2 Congreso Argentino de Fitopatologa

2 Congreso Argentino de Fitopatologa | Libro de Resumenes | 1, 2 y 3 de junio de 2011 | Mar del Plata, Buenos Aires, Argentina 414 p. ; 15 x 21 cm. ISBN 978-987-544-389-1

Fecha de catalogacin:26 /05/11 Queda hecho el depsito que marca la Ley 11.723 de Propiedad Intelectual. Prohibida su reproduccin total o parcial por cualquier medio o mtodo, sin autorizacin previa de los autores. Primera Edicin: Mayo 2011

Impreso en la Argentina Arte , Composicin y Diagramacin: Flavio Diez - [email protected]

Impreso en: Grfica Tucumn Tucumn 3011 | Mar del Plata2

ASOCIACIN ARGENTINA DE FITOPATLOGOS (AAF)Comisin Directiva 2009-2012Presidente: Ing. Agr. Luis CONCI Vicepresidente: Ing. Agr. Guillermo MARCH Secretario: Ing. Agr. Mercedes SCANDIANI Tesorero: Ing. Agr. Raquel HAELTERMAN Vocales Titulares Captulo NOA: Ing. Agr. Noem BEJARANO Captulo NEA: Lic. Bot. Ernestina GALDEANO Captulo Litoral: Ing. Agr. Rosanna PIOLI Captulo Centro: Ing. Agr. Adriana MARINELLI Captulo Buenos Aires: Ing. Agr. Marta ASTIZ GASS Captulo Cuyo: Ing. Agr. Gabriela LUCERO Captulo Patagonia: Ing. Agr. Mirta ROSSINI Comisin Revisora de Cuentas Titulares Biol. Fabian GIOLITTI Ing. Agr. Claudio ODDINO Suplente Ing. Agr. Ana Mara ROMERO Junta Electoral Titulares Biol. Silvina VARGAS GIL Ing. Agr. Pablo H. PIZZUOLO Ing. Agr. Jos CATACATA Suplente Ing. Agr. Ceferino FLORES

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COMISIN ORGANIZADORA 2DO CONGRESO ARGENTINO DE FITOPATOLOGAPresidente: Dra. Azucena del C. RIDAO Vice Presidente: Dr. Alberto R. ESCANDE Secretaria: Ing. Agr. Andrea SALVALAGGIO (M. Sc.) Tesorera: Ing. Agr. Mnica COLAVITA (M. Sc.) Pro-Tesorera: Ing. Agr. Raquel HAELTERMAN Comisin Cientfica Ing. Agr. Alicia MELEGARI (M. Sc.); Dr. Eliseo CHAVEZ; Dr. Rolf DELHEY; Ing. Agr. Juan ANNONE (M. Sc.); Dr. Antonio IVANCOVICH; Dr. Sergio LENARDN; Dr. Eduardo R. WRIGHT; Dra. Ana ROMERO; Dra. Beatriz PREZ; Dra. Adriana ALIPPI; Dra. Anala PERELL; Ing. Agr. Gladys LORI Comisin Logstica Ing. Agr. Facundo QUIROZ (M. Sc.) Lic. Carla MARINGOLO (M. Sc.) Ing. Agr. Carlos MANEIRO Sr. Pedro IBEZ Comisin de Divulgacin y Prensa Lic. Marina MONTOYA (M. Sc.) Sr. Pedro IBEZ Colaboradores Dr. Luis CONCI; Ing. Agr. Marta ASTIZ GASS; Ing. Agr. Carolina TROGLIA (M. Sc.); Dra. Mercedes SCANDIANI; Ing. Agr. Florencia LUCCA (M. Sc.); Ing. Agr. Marcelo CARMONA (M. Sc.); Ing. Agr. Silvia R. FRAYSSINET (Mag.); Ing. Agr. Pablo GRIJALBA (M. Sc.); Ing. Agr. Sergio RAMOS (M. Sc.); Ing. Agr. Natali LZZARO; Sr. Ignacio ERREGUERENA

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Bienvenidos al 2 Congreso Argentino de Fitopatologado

Estimados Colegas Una puerta hacia la sanidad vegetal es el lema que convoca hoy el 2do Congreso Argentino de Fitopatologa. Aunque principiantes en esto de organizar congresos, reuniones de Fitopatologa se han realizado desde fines de la dcada de 1960. Bueno es, transitado el bicentenario de la patria, valorar tambin nuestra historia y resaltar que, quienes nos precedieron, en tiempos difciles, con gran esfuerzo intentaron de una manera u otra, la integracin de los fitopatlogos. Tanto participando en las Jornadas Fitosanitarias Argentinas, como junto a congresos de la Asociacin Latinoamericana de Fitopatologa, ambos han alcanzado sus 13 ediciones (la ALF organizando aqu, en Buenos Aires en 1982 y en Carlos Paz, Crdoba, en 2005). En un comienzo como talleres de la Asociacin Argentina de Fitopatologa (AAF). Luego, en 2003, la AAF refundada como Asociacin Argentina de Fitopatlogos con sede en Crdoba, logr concretar la meta tan largamente postergada y realiz exitosamente el 1er Congreso Argentino de Fitopatologa. La Comisin Directiva de la AAF, en representacin del captulo Buenos Aires y con el voto de los jvenes, me ha conferido el honor de presidir este Congreso. Es la nica reunin cientfica formal de la especialidad y aspira ser un foro de debate de todas las especialidades de la fitopatologa. Siempre con los pies sobre la tierra, no perdiendo el contacto con los problemas actuales de la agricultura y los agricultores, con la mira puesta hacia el concepto de mantener el estado saludable de las plantas. Ante un mundo convulsionado, impredecible por el cambio climtico, Argentina como parte de la Amrica Latina, est llamada a mitigar el hambre de una poblacin mundial, que se estima alcanzar los 9.100 millones de personas para 2050. Es nuestra agricultura pionera, pero son los patgenos quienes tambin evolucionan en paralelo, aunque secretamente y son los que compiten por nuestros alimentos, nuestra vestimenta y en definitiva por nuestro bienestar general. Hemos organizado las actividades de manera que no haya sesiones simultneas, por lo que estn dispuestas en el tiempo, en forma lineal. Se han incluido temas de inters general, enfocados a nuestros cultivos extensivos decisivos, cereales y oleaginosos, as como problemticas puntuales de algunos de los cultivos relevantes del sur de Buenos Aires hacia el sur del pas, hortcolas y frutales de pepita. La enseanza de la fitopatologa, aunque no expuesta en la palestra, est presente e implcita en cada una de nuestras actividades tanto de grado como de posgrado. En representacin de la Comisin Organizadora que trabaj arduamente en la concrecin de este evento, debo agradecer a todas las personas, instituciones y empresas que nos apoyaron, sin las que este Congreso no hubiese sido posible. Hemos tenido, una respuesta que ha alcanzado las expectativas, la que se ve reflejada en la cantidad de resmenes de los diversos temas enviados por los investigadores y docentes nacionales y tambin de nuestros pases hermanos. Deseo que los temas sean de vuestro inters y espero que esta reunin sea una experiencia enriquecedora, que disfruten del intercambio cientfico de las ideas, de la compaa de nuevos contactos y de los viejos colegas amigos. Adems, que puedan recrearse en el circuito Mar y Sierras, gozar de la fresca brisa marina de fines de otoo de La Ciudad Feliz y de la calidez de su gente. Cordialmente

Dra. Azucena del C. Ridao

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AUSPICIOS INSTITUCIONALESUniversidad Nacional de Mar del Plata, Facultad de Ciencias Agrarias | OCA N 544/10 Instituto Nacional de Tecnologa Agropecuaria (INTA) Res. N 143/11 Consejo Nacional de Investigaciones Cientficas y Tcnicas (CONICET) Fondo para la Investigacin Cientfica y Tcnolgica (FONCYT) Universidad Nacional del Litoral, Facultad de Ciencias Agrarias Res. N 167/10 Universidad Nacional de Cuyo, Facultad de Ciencias Agrarias Res. N 312/10 Universidad Nacional de Rosario, Facultad de Ciencias Agrarias Res. N D-378/2.010 Universidad Nacional del Centro de la Provincia de Buenos Aires, Facultad de Agronoma | Res. N 127/2010 Universidad de Buenos Aires, Facultad de Agronoma Academia Nacional de Ciencias Asociacin Argentina de Proteccin Vegetal y Ambiental (ASAPROVE) Bolsa de Cereales de Buenos Aires

Estacin Experimental Agroindustrial Obispo Colombres (EEAOC) | Res. N15861/10 Sociedad Argentina de Gentica (S.A.G.)6

INSTITUCIONES / EMPRESAS PATROCINANTESInstituto Nacional de Tecnologa Agropecuaria (INTA) Consejo Nacional de Investigaciones Cientficas y Tcnicas (CONICET) Fondo para la Investigacin Cientfica y Tcnolgica (FONCYT) DuPont Argentina S. A. BAYER S. A. Argentina BASF Argentina S. A. RIZOBACTER Argentina S. A. Syngenta Agro S. A. ASOCIADOS DON MARIO S. A. BIOREBA S. R. L. Latin America Biocientfica S. A. NOVOZYMES Magn Argentina Lab. PASTOR AGRODIAGNOSTICOS GE Healthcare RURALEX / FAGOS

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CONFERENCIASThe impact of the climate change on crop diseases with a focus on diseases of wheat and oilseed rape (colza-canola). Jon S. West ................................................................................ Research innovations in the detection of seedborne pathogens and the elucidation of their epidemiology. Garry P. Munkvold....................................................................... Capacities and networks for plant disease diagnostics Sally A. Miller............................................................................... Re-emergence of northern stem canker on soybeans in the United States Thomas Chase............................................................................

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THE IMPACT OF THE CLIMATE CHANGE ON CROP DISEASES WITH A FOCUS ON DISEASES OF WHEAT AND OILSEED RAPE (COLZA-CANOLA)J. S. West, Rothamsted Research, Harpenden, UK. E-mail: [email protected]

In the UK, climate change is predicted to lead to milder, wetter winters and hotter drier summers with more extreme weather events. Crops will respond by advancing growth stages, with current wheat cultivars flowering 2-weeks earlier and harvested three weeks earlier than traditionally. Adoption of Mediterranean-type varieties of cereals to avoid heat stress at flowering will advance these growth stages by another 2 weeks. Elevated CO2 concentrations will increase or maintain crop productivity, despite the earlier harvest, as long as diseases and pests are controlled. Cultivation of current arable crops will probably move slightly to the north, with potential new crops such as maize and sunflower grown in the south of England. Many diseases will, on average, change in importance only slightly as the regions of production of particular crops will tend to move northwards. However, the risk of newly introduced diseases establishing is increased by climate change so it is important to maintain and even increase statutory crop monitoring, quarantine and surveillance and to ensure that crop genotype collections are maintained with as much diversity as possible for future breeding programmes. More extreme or variable weather may make certain diseases (e.g. rusts and powdery mildews) more sporadic and encourage those that develop quickly in warm conditions. Insect-vectored virus and phytoplasma diseases will become more important due to greater vector activity. Many contrasting effects of different aspects of climate change on different stages in the life-cycle of a particular pathogen mean that some detailed knowledge of the pathogens life-cycle and ideally climate-based disease-progress models is needed to make predictions of likely effects of climate change. Since the timing of key crop growth stages will also change, for accurate predictions of effects on diseases, disease progress models should be combined with crop growth models and climate simulations. We did this for 11


important diseases of wheat and colza (canola). We found that the severity of blackleg, caused by Leptosphaeria maculans would increase substantially due to increased thermal time after infection (Butterworth et al. 2010). This may also be exacerbated by dysfunction of host resistance, conferred by some resistance genes at elevated temperatures (Huang et al. 2006). We also found that earlier flowering of winter wheat would mean that suitable sporulation and infection conditions for Fusarium graminearum would increase slightly and additionally, increased cultivation of grain maize would substantially increase inoculum production, leading to greater disease incidence (Madgwick et al. 2011). The findings for these two disease systems were extrapolated to interpret likely changes in other systems. We predict that rusts and powdery mildews will become more severe after mild weather in winter and early spring (assuming some dry days will allow dispersal) but less severe after particularly hot, dry weather in summer. Epidemics of these obligate pathogens will therefore depend on combinations of favourable and unfavourable summer and winter weather over more than one season so that epidemics of these diseases will become more sporadic. In contrast, summer droughts may favour certain pathogens that produce lesions and fruiting bodies on dead plant tissue because reduced destruction of crop residues (by molluscs and other invertebrates) will lead to increased inoculum production in the autumn. Generally there is a knowledge gap for understanding pathogen survival and the timing of spore release to infect subsequent crops, as different responses to the climate by the pathogen and crop could lead to more or less infection (less or more disease-escape). Where crops remain in their original regions or particularly at the southern parts of their distribution, generally warmer conditions will increase severity of autumn and winter-infecting root and stem rots, while spring-infecting root and stem rots will advance with earlier crop growth and so not change in relative severity. However, yield losses from these diseases will also increase due to greater and earlier transpiration stress caused by heat or drought. Effects of increased CO2 concentrations on plant pathogens also requires further research as effects on systems already studied vary greatly from one pathogen to another. Increased CO2 will lead to denser crop canopies, which 12

will encourage a range of foliar diseases. Due to milder winters that will advance both crop growth and disease epidemics, early spring fungicide sprays could increase in importance. Leaf production in mid-late spring may also become so rapid that the timings of latespring and early summer fungicide sprays (relative to growth stage) will need revision in order to achieve optimal protection. Introductions of new pathogens (unknown unknowns), changes in farm practices including new crops grown, complexities of climate change projections and the biotic responses to this make prediction of the future impact of climate change on plant diseases relatively uncertain. It is therefore also important to create funding mechanisms that can allow a rapid response to research new diseases. Climate change offers the opportunity to increase crop productivity and diversify cropping systems, and emphasises the need to produce arable crops with a low carbon-footprint, while maintaining a secure and stable food supply. ReferencesButterworth MH, Semenov MA, Barnes A, Moran D, West JS, Fitt BDL. 2010. North South divide: contrasting impacts of climate change on crop yields in Scotland and England J. R. Soc. Interface 7: 123-130. Yong-Ju Huang, Neal Evans, Zi-Qin Li, Maria Eckert, Anne-Marie Chvre, Michel Renard, Bruce D. L. Fitt. 2006 Temperature and leaf wetness duration affect phenotypic expression of Rlm6 -mediated resistance to Leptosphaeria maculans in Brassica napus. New Phytologist 170: 129141. Madgwick J, West JS, White R, Semenov M, Townsend JA, Turner JA, Fitt BDL. 2011. Future threat; direct impact of climate change on wheat fusarium ear blight in the UK. European Journal of Plant Pathology (in press).DOI 10.1007/s10658-0109739-1

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RESEARCH INNOVATIONS IN THE DETECTION OF SEEDBORNE PATHOGENS AND THE ELUCIDATION OF THEIR EPIDEMIOLOGYG. P. Munkvold, Iowa State University Seed Science Center, Ames, IA, USA. E-mail: [email protected]

The importance of seeds as a means of pathogen dissemination has been recognized for centuries, but there have been many obstacles to effectively managing this risk. Seed health testing has become a critical tool for efforts to prevent the movement of pathogens in seeds and to assess seed quality. Methods for seed health testing have evolved and improved in a continuous effort to increase sensitivity, specificity, precision, and efficiency. Numerous nucleic-acid based detection methods have been developed for seed health testing, and their application has been facilitated by integrating conventional or realtime PCR with other technologies (e.g., BIO-PCR, IMS-PCR,MCHPCR). PCR-based assays are widely used in research and commercial settings, but have not been used extensively in phytosanitary certification, for a variety of reasons that will be discussed. One obstacle to the use of PCR-based seed health tests in phytosanitary settings has been the lack of epidemiological knowledge connected to test results. Interpretation of any seed health test requires epidemiological knowledge, and development of this knowledge has lagged behind the availability of advanced testing technologies. Ideally, seed health testing should be accomplished and interpreted within a framework that takes into account all the quantifiable factors that may influence the risk associated with seedborne infection. Developing this framework can be challenging and slow. However, in recent years, PCR-based methods and pathogen marker technologies are increasingly being applied to epidemiological research on seedborne pathogens; e.g., seed transmission mechanisms, the influence of external biotic and abiotic factors on seed transmission, and tracking progress of seedtransmitted pathogens. In this presentation, I will discuss innovations in seed health testing, as well as the use of advanced technologies to better understand epidemiology of seedborne diseases. Examples will include bacterial fruit blotch of cucurbits (caused by Acidovorax avenae subsp. citrulli), seed transmission of Fusarium verticillioides in maize, Pea Seedborne Mosaic Virus, and others. Innovative epidemiological 15


research on seedborne pathogens has employed the creative use of real-time PCR and BIO-PCR, tracking pathogens strains through molecular markers or transformation with genes for fluorescent protein expression, and in situ hybridization (Munkvold, 2009). These innovations continue to improve seed health testing methods and their interpretation, and improved epidemiological knowledge can facilitate accurate risk assessment, leading to informed decisions on phytosanitary regulations. Efforts to reform phytosanitary regulations depend on accurate risk assessment, which ultimately facilitates safe and efficient international seed trade and supports the use of highquality seed for all types of farmers. References:Munkvold, G.P. 2009. Seed pathology progress in academia and industry. Annu. Rev. Phytopathol. 47: 285-311

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CAPACITIES AND NETWORKS FOR PLANT DISEASE DIAGNOSTICSS. A. Miller, The Ohio State University, Ohio Agricultural Research and Development Center, Wooster, Ohio USA. E-mail: [email protected]

Plant diseases cause significant economic losses in agronomic and horticultural crops and forests, and damage natural ecosystems worldwide (Strange and Scott 2005). Both endemic and invasive pathogens can be serious threats, depending on host plant susceptibility and environmental conditions. Globalization, climate change, human mobility and pathogen and vector evolution contribute to both the increased spread of invasive pathogens and the risk of significant environmental and economic impact. It is imperative that the physical and human capacity to diagnose plant diseases meet the expanding needs worldwide as population growth and urbanization with concomitant loss of farmlands and forests put pressure on remaining cropping and forest systems to be highly productive. They are the cornerstone of both routine crop protection from endemic pathogens and avoidance of catastrophic losses due to the introduction of invasive pathogen species. Early and accurate diagnoses and effective pathogen surveillance are necessary on local, regional and global scales to predict disease outbreaks and allow timely deployment of mitigation strategies. The inability to effectively diagnose diseases and detect both endemic and invasive pathogens ultimately results in 1) delays and/or errors in identifying and deploying appropriate control tactics such as resistant cultivars and pesticides, and 2) missed opportunities to prevent the entry of invasive pathogens or contain them once arrived in a country. Plant safeguarding against invasive pathogens is the responsibility of national plant protection organizations (NPPOs) in each country. NPPOs function as regulatory agencies, but also conduct pathogen surveillance, pest risk analyses, inspect, treat and certify exports, inspect imports and enforce quarantines if necessary. In the United States, this function is shared between the Departments of Agriculture and Homeland Security, which coordinate with individual state departments of agriculture. These agencies are assisted by the 17


National Plant Diagnostic Network (Stack et al., 2006), which is a three-tiered network of diagnostic laboratories at the state, regional and national levels. Most of the diagnostic laboratories are operated by plant pathologists in Land Grant Universities in each state. Members conduct pathogen surveillance activities, train first responders and develop and utilize standard operating procedures (SOPs) for important invasive and endemic pathogens. In Europe, NPPOs network with one another through the European and Mediterranean Plant Protection Organization (EPPO). The International Plant Protection Convention (IPPC), a function of the Food and Agriculture Organization (FAO) of the United Nations, governs official international actions to limit the movement of plant pathogens. The 170 countries that have adopted the IPPC (http://www.fao.org/Legal/TREATIES/004s-e.htm), form a de facto network under the umbrella of the IPPC Secretariat and operating under international standards for phytosanitary measures. The costs of plant safeguarding activities such as pathogen surveillance are high (Anon, 2008), and many developing countries limit their trade opportunities due to their inability of provide accurate lists of pathogens and pests within their borders. The second major function of diagnostics is to provide accurate information to guide disease management decision-making. Deploying an effective integrated pest management (IPM) program requires first the accurate and timely identification of the disease causal agent. Effective use of IPM can result in substantial benefits, including economic and environmental gains due to higher yield and quality of product and reduced use of pesticides. Community-based IPM programs require surveillance of target pathogens through a network of professionals on alert for entry of the pathogen. For example, soybean rust, caused by Phakopsora pachyrhizi, is monitored throughout US soybean production areas though a series of sentinel plots (rust-susceptible soybean cultivars) that are scouted routinely and scouting reports made available to the community through a public web portal, the IPM Pest Information Platform for Extension and Education (ipmPIPE; http://sbr.ipmpipe.org/cgi-bin/sbr/public.cgi). Although soybean rust has yet to cause significant losses in the United States, despite its devastating impact in Brazil, for example, the ipmPIPE network saved US soybean growers $millions in unnecessary fungicide applications (Roberts et al., 2006). There are currently six ipmPIPE networks in the 18

US, monitoring critically important diseases and pests of soybeans, pecans, legumes, cucurbits and corn (http://www.ipmpipe.org/). The cucurbit ipmPIPE monitors the entry and movement of the downy mildew pathogen Pseudoperonospora cubensis in the eastern half of the US and in California. The cucurbit downy mildew (CDM) ipmPIPE (http://cdm.ipmpipe.org/) combines sentinel plot and commercial field reports of downy mildew with weather data to predict the risk of disease occurrence (Ojiambo et al., 2009). Reports of CDM must be confirmed microscopically by pathologists trained in identification of P. cubensis. Through this network it has been possible to map the introduction and movement of P. cubensis from 1) the southeastern US through the Mid-Atlantic and Northeast regions, and 2) within the Midwestern states of Ohio and Michigan. The availability of this information allows cucurbit growers to make the most cost-effective decisions on the use of fungicides to manage the disease. The quality of plant disease diagnoses and ultimately their usefulness in both plant safeguarding and disease management decisionmaking is a function of 1) human resources, 2) technology and 3) infrastructure. For all but the most simple and obvious diagnostic problems, well-trained individuals, readily available technology and/or adequate infrastructure for conducting diagnostic tests and protocols are required. Significant gaps in capacity to diagnose plant diseases exist in both the developing (Canale, 2003) and developed (Sheldrake et al., 2003) world. In the US, for example, human capacity for diagnostics declined as resources were directed toward basic research at the expense of applied research, and support for diagnostic clinics within the Land Grant University system was reduced. Concerns over biosecurity beginning in 2001, however, resulted in an influx of federal support of plant disease diagnostic clinics in these Universities and the organization of the NPDN. In many developing countries, lack of investment in agricultural research, education and extension has resulted in understaffing and lack of training opportunities for plant pathologists/diagnosticians (Canale, 2003). India may be an exception, as diagnostic capacity is beginning to increase as plant health clinics are being established in the private and public sectors throughout the country (Boa, 2007). The lack of human capital will not be remedied in the near future by a large influx of well-trained diagnosticians, particularly in the developing world. Therefore, sharing of expertise 19


across borders through well-supported networks can compensate for the lack of human capacity in a given country. For example, the International Plant Diagnostic Network (IPDN), established in 2004, assists local diagnosticians through training, diagnostic technology research and development, preparation and sourcing of reference materials and sharing of diagnostic expertise in 14 countries (Miller et al., 2010). Technology development, in terms of both platforms (molecular, serological) and breadth of pathogens targeted has been rapid and extensive during the past 2-3 decades. Field-ready serological assays such as Lateral Flow Devices (LFDs) can be used to guide disease management decision-making or in support of plant safeguarding (inspections, surveillance). For example, a Phytophthora spp. LFD served as a pre-screening tool at ports of entry into the UK to identify potential P. ramorum-infected woody plants. Samples positive with the LFDs were sent to a lab for determination of species by more specific PCR assays (Lane et al., 2007). A highly specific PCR assay to diagnose the invasive banana wilt pathogen Xanthomonas campestris pv. musacearum (Lewis Ivey et al., 2010) has been used to confirm identity of the pathogen as it spread into additional countries (Carter et al., 2009). Molecular tools such as isothermal DNA amplification techniques (Vincelli and Tisserat, 2008) promise to provide high sensitivity and specificity, as well as speed and ease of use for infield applications. The cost of LFDs, other serological tests and DNA amplification assays continue to decline, making them affordable in many situations. However, these costs are too high for widespread adoption of the assays in the developing world, at least in the near term. The exception may be for high-value crops such as glasshouse tomatoes and ornamental plants being grown in these countries. Finally, adequate infrastructure is necessary for well-functioning diagnostic laboratories. This includes not only the physical space but availability of well-maintained equipment such as microscopes, incubators and thermal cyclers, necessary glassware and consumables including media, reagents, etc. Most diagnostic laboratories in developed countries are sufficiently equipped and well-maintained for at least routine laboratory analyses. Laboratories within the NPDN and other networks are connected via internet-enabled microscopes that 20

facilitate sharing of digital images among experts within the network, often through specialized web portals that also serve as databases for diagnostic information. However, in developing countries this is rarely the case. In surveys of diagnostics professionals conducted in Africa, reference materials, access to high speed internet, cameras, computers, specialized equipment (such as thermal cyclers) and general supplies and consumables was considered inadequate by 50% or more of the respondents (Miller et al., 2010). There are several effective diagnostic networks in existence today throughout the world. Those most successful and most likely sustainable over the long term enjoy significant government investment. Case studies of several diagnostic networks in the developed and developing world indicate that resource and information sharing can increase the effectiveness of individual diagnostic programs at the local, regional, national and international levels. Effective diagnostic networks are vertically integrated, from well-trained first responders such as farmers and extension personnel in the field to diagnosticians and specialists capable of providing management advice. Secure and trusted communications travel in both directions. The increased capacity generated from this exchange of information can be used to update new disease reports, optimize surveillance strategies and develop pest risk analyses.Anonymous. 2008. An independent review of New Zealands biosecurity surveillance systems plants. Biosecurity New Zealand. http://biosecurity.govt.nz/pestsdiseases/surveillance-review/plants.htm. Boa, E. 2007. Plant healthcare for poor farmers: An introduction to the work of the Global Plant Clinic. APSnet Feature, http://www.apsnet.org/online/feature/clinic/. Canale, F. 2003. Phytosanitary capacity evaluation: the tool, its results and its relation to alien invasive species. In Identification of Risks and Management of Invasive Alien Species Using the IPPC Framework. Proceedings of the workshop on invasive alien species and the International Plant Protection Convention, Braunschweig, Germany, 22-26 September 2003, pp. 186-90. Rome, Italy: FAO. Carter, B. A., Reeder, R., Mgenzi, S.R., Kinyua, Z. M., Mbaka, J. N., Doyle, K., Maina, M., Valentine, G., Aritua, V., Lewis Ivey, M. L , Miller, S. A. and Smith, J. J. 2009. Identification of Xanthomonas vasicola (formerly X. campestris pv. musacearum), causative organism of banana xanthomonas wilt, in Tanzania, Kenya and Burundi. New Disease Reports http://www.bspp.org.uk/publications/new-disease-reports/ ndr.php?id=019025 Lane, C.R., Hobden, E., Walker, L., Barton, V.C., Inmana, J.A., et al. 2007. Evaluation of

References

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a rapid diagnostic field test kit for identification of Phytophthora species, including P. ramorum and P. kernoviae at the point of inspection. Plant Pathology 56: 82835. Lewis Ivey, M. L., Tusiime, G. and Miller, S. A. 2010. A PCR assay for the detection of Xanthomonas campestris pv. musacearum in bananas. Plant Dis. 94:109-114. Miller, S. A., Beed, F. and Harmon, C. L. 2009. Plant disease diagnostic capabilities and networks. Annu Rev. Phytopathology 47:15-38. Miller, S. A., Kinyua, Z. M., Beed, F., Harmon, C. L., Xin, J., Vergot, P., Momol, T., Gilbertson, R. and Garcia, L. 2010. The International Plant Diagnostic Network (IPDN) in Africa: Improving capacity for diagnosing diseases of banana (Musa spp.) and other African crops. Acta Hort. 879:341-347. Ojiambo, P., Kanetis, L. and Holmes, G. 2009. Forecasting long distance movement of Pseudoperonospora cubensis and the Cucurbit ipmPIPE. Phytopathology 99:S171. Roberts, M.J., Schimmelpfennig, D., Ashley, E. and Livingston, M. 2006. The value of plant disease early-warning systems. United States Department of Agriculture Economic Research Service Report 18, 38 pp. http://www.ers.usda.gov/ publications/err18/err18.pdf. Sheldrake, R., Williams, M. and Turner R. 2003. Developing a world class plant pathology diagnostics network. http://www.planthealthaustralia.com.au. Stack, J.P., Cardwell, K., Hammerschmidt, R., Byrne, J., Loria, R. et al. 2006. The National Plant Diagnostic Network. Plant Dis. 90:128-36. Strange, R.N. and Scott, P.R. 2005. Plant disease: a threat to global food security. Annu. Rev. Phytopathol. 43: 83-116. Vincelli, P. and Tisserat, N. 2008. Nucleic acid-based pathogen detection in applied plant pathology. Plant Dis. 92: 660-69.

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RE-EMERGENCE OF NORTHERN STEM CANKER ON SOYBEANS IN THE UNITED STATEST. Chase, South Dakota State University, Plant Science Department, Brookings, South Dakota, United States. E-mail: [email protected]

Introduction

The apparent re-emergence of Northern stem canker (NSC) in the Northern Plains region of the United States has come to the attention of farmers, agronomists, and plant pathologists over the past decade. Outbreaks of the disease have been sporadic and unpredictable but severely damaging to individual soybean growers in many cases. Because of the late development of symptoms and poor awareness of the disease, Northern stem canker is often overlooked or misdiagnosed by farmers and agronomists. The potential for increase in prevalence, incidence and severity of NSC coupled with the unpredictable nature of outbreaks is of considerable concern and prompted research studies at South Dakota State University funded by the South Dakota Soybean Research & Promotion Council. Stem canker was a serious disease problem on soybeans in the Midwest, Northern Plains and Ontario beginning in the 1950s when intensive soybean production was fairly new. The disease was brought under control presumably by removing extremely susceptible varieties such as Blackhawk and Hawkeye from production (Kulik,1983). For years afterward, Northern stem canker remained a rare disease problem on soybean, although the causal pathogen could usually be isolated from seed lots at low frequency. Northern stem canker is a sporadic, but high-intensity soybean disease Late in the 1998 and 1999 growing seasons pathologists were asked to investigate cases of early maturity reported by soybean growers in South Dakota. It became clear that these crops were not maturing early, but instead were experiencing a high incidence of stem canker or very similar disease. Stand counts of 50-90% incidence of girdling cankers at lower leaf nodes were not uncommon in these fields. Yield 23


loss estimates of up to 50-65% were reported by some soybean growers. Several additional cases were seen in the early 2000s and numerous putative cultures of Diaporthe/Phomopsis were isolated. The overwhelming majority of isolates had cultural characteristics consistent with Diaporthe phaseolorum var. caulivora (Dpc), the causal agent of Northern stem canker. Isolates of Phomopis longicolla were also recovered from cankers. Inoculation trials, utilizing the toothpick method (Crall, 1952) established pathogenicity of these putative Dpc isolates. Phomopsis longicolla isolates, when similarly inoculated, did not cause canker symptoms or death of inoculated plants. Additional outbreaks of NSC were documented over the next several years with Dpc type isolates consistently being isolated from cankers. The identity of isolates was confirmed using the PCR-RFLP technique developed by Zhang et al. (1998). Cultures of the two RFLP types Dpc A and Dpc B (Zhang et al., 1998) were isolated 61% and 16 % respectively from cankers. Phomopsis longicolla composed 14.5% of total isolates. No isolates of the Southern stem canker pathogen, Diaporthe phaseolorum var. meridionalis (Dpm) have been identified in South Dakota to date. These damaging high-incidence outbreaks of NSC in South Dakota have been relatively rare. Usually only one or two such outbreaks have been documented each year. Characteristically, disease is evenly distributed throughout these fields, disease incidence reaches 50-90% and yield losses can be as high as 65%. One of the characteristic and truly puzzling aspects of high-incidence outbreaks is the cropping history of the impacted fields. In nearly every case, the field in which a high-incidence outbreak has occurred has not had soybeans as a crop for several years immediately preceding. Often these fields have been in a corn/alfalfa rotation. In 2009 a field with a high-incidence field was documented near the town of Castlewood, South Dakota. Disease incidence reached ca. 90% with nearly each soybean stem completely girdled and killed. A yield of approximately 2.7 MT/hectare was expected based on normal growing conditions. Actual yield was 1 MT/hectare. Remarkably, this field had been in enrolled in the Conservation Reserve Program (Anonymous, 24

2008) for 11 years prior to 2009, with plant populations comprised of Intermediate wheat grass and an old variety of alfalfa called Grimm. In all cases where voucher seed from high-incidence outbreaks could be examined, the percentage of seedborne infection was too low to account for seed as a source of inoculum. South Dakota adapted soybean germplasm is very susceptible to Northern stem canker Extensive pathogenicity studies of soybean varieties entered in annual crop performance testing program at South Dakota State University over three seasons (2004-2006) demonstrated that nearly all prospective commercial germplasm had a high degree of susceptibility. These studies were based on toothpick inoculations of field grown plants (Chase and Geppert, 2007). Although the toothpick method may be a good measure of resistance to spread of DPC within plants, it is not clear how well it represents the actual infection process as it occurs naturally. No evidence of major resistance genes to Northern stem canker was found in these studies. What does this mean for soybean growers who are at risk for Northern stem canker? It is clear that under some circumstances Northern stem canker can be a very damaging disease of soybeans. Given the widespread occurrence of the pathogen in soybean seed and as latent infections in immature plants, one might ask the question why has Northern stem canker not become more damaging in areas where soybeans are intensively cultivated? In point of fact, it seems that NSC only becomes a real factor when soybeans are planted in fields where soybean residues and ostensibly high concentrations of Dpc inoculum must have been lacking. What is the source of inoculum and why is canker formation triggered so uniformly in these fields? Several researchers have reported high isolation frequency of Dpc from apparently healthy immature soybean plants (Sinclair, 1991), and it is also known that seedborne infection occurs under conditions where visible disease is lacking (Xue et al., 2007). It is tempting to hypothesize that Dpc is primarily an endophytic fungus, capable of infecting soybeans early in the growing season, but then normally surviving as an. It may be that only under specific environmental or biological conditions that Dpc is triggered to be actively pathogenic 25


and to cause cankers. Many endophytyic fungi cause little apparent disease in infected plants and only become visible as they fruit on senescing or dead tissues. The closely related fungus Diaporthe phaseolorum var. sojae (Dps), the causal agent of pod & stem blight is a good example. As a corollary to this hypothesis it may be that other endophytic fungi and/or bacteria build up as resident micro-organisms in continued soybean cultivation and suppress Dpc. Hildebrand (1954) demonstrated a higher occurrence of pathogenic Diaporthe in soybeans grown on soils not previously planted to soybeans than in plots where soybeans had been grown continuously for four years. Alternatively, there may be a specialized set of physiological stresses associated with soybeans in the first rotation that trigger Dpc to become actively pathogenic. At this point, these concepts are purely speculative and much work will be required to test them. It is clear that a standard model of a residue born stem disease will not suffice to explain the occurrence of Northern stem canker in soybeans in the North Central region of the United States. ReferencesAnonymous. 2008. Conservation Reserve Program. Natural Resources Conservation Service. USDA. http://www.nrcs.usda.gov/programs/CRP/ Chase, T.E. and R.L Geppert. 2007. Susceptibility to Northern stem canker in South Dakota soybean varieties. Phytopathology 97:S20 Chase, T.E., and C. Tande. 2001. Occurrence of stem canker on soybeans in South Dakota. Phytopathology 91:S15. Crall, J.M. 1952. A toothpick tip method of inoculation. Phytopathology 42:5-6. Hildebrand. 1954. Observations on the occurrence of the stem canker and pod and stem blight fungi on mature stems of soybean. Plant Disease Reporter 38: 640-646. Kulik, M.M. 1983. The current scenario of the pod and stem blight-stem canker-seed decay complex of soybean. International Journal of Tropical Plant Diseases 1:1-11. Sinclair, J.B. 1991. Latent infections of soybean plants and seeds by fungi. Plant Disease 75:220-224. Xue, A.G., M.J. Morrison, E. Cober, T.R. Anderson, S. Rioux, G.R.Ablett, I. Rajcan, R. Hall and J.X. Zhang. 2007. Frequency of isolation of species of Diaporthe and Phomopsis from soybean plants in Ontario and benefits of seed treatments. Canadian Journal of Plant Pathology 29: 354-364. Zhang, A.W., L. Riccioni, W.L. Pedersen, K.P. Kollipara and G. L. Hartman. 1998. Molecular identification and phylogenetic grouping of Diaporthe phaseolorum and Phomopsis longicola isolates from soybean. Phytopathology 88:13061314.

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MESAS REDONDAS INOCUIDAD ALIMENTARIA, MICOTOXINASModeradora: Mercedes Scandiani

Fusarium head blight in wheat and mycotoxins. Sofa Chulze 29 Fusarium diseases and their my cotoxins in maize ears Gary P. Munkvold .................................... 31 Food innocuity and mycotoxins: a view from Brazil Ludwing H. Pfenning y L. R.Batista.... 33

CONTROL BIOLGICOModeradora: Laura Gasoni

El control biolgico de enfermedades, en comparacin con el de malezas y de plagas animales Rolf Delhey........................................................... 35 Situao e desafios para o biocontrole de doenas de plantas na Amrica do Sul Wagner Bettiol ...................................................... 37 Biocontrol de fitopatgenos en Cuba Marusia Stefanova ............................................... 39 Controle biolgico no Brasil: nmeros de mercado e o potencial de crescimento Danilo Scacalossi Pedrazzoli ................ 4127


Biocontroladores: puede convivir el paradigma del control qumico con el paradigma del control biolgico? Gustavo Gonzlez Anta....................................... 43 REDES DE DIAGNSTICO, ROL DEL ASESOR O EXTENSIONISTA Moderadora: Azucena del Carmen Ridao Diagnostic networks the role of the advisor Sally Miller.........................................................

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Identificacin de enfermedades: rol del profesional de la agronoma y de los laboratorios de anlisis Alberto Escande........................... 47 Red Nacional de Proteccin Vegetal (RedNPV) Vilma C. Conci.......................... 49 Cuando la red nos contiene Carlos Maneiro............................. Redes de diagnostico, rol del asesor o extensionista Miguel Redolatti...............................................

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Participacin y responsabilidad del sector privado en la obtencin de una mirada sistmica a la salud de los cultivos: la experiencia de una empresa privada en el diagnstico de enfermedades de la semilla de papa. Ana Mara Escarr.................................................. 55

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FUSARIUM HEAD BLIGHT IN WHEAT AND MYCOTOXINSS.N. Chulze, Departamento de Microbiologa e Inmunologa, Facultad de Ciencias Exactas Fsico-Qumicas y Naturales. Universidad Nacional de Ro Cuarto, Ruta 8 Km 601 (5800) Ro Cuarto-Crdoba, Argentina. E-mail: [email protected]

The Fusarium head blight (FHB) of wheat is a growing treat to the world`s food supply because recent outbreaks in different regions of the world including Asia, Europe, Canada, North and South America. In Argentina, several FHB epidemics occurred in the last 50 years, causing yield losses and price discount due to reduced seed quality. Gibberella zeae (Schwein.) Petch (anamorph Fusarium graminearum Schwabe), lineage 7, within the Fusarium graminearum complex, is the principal causal agent of FHB in Argentina. Studies using vegetative compatibility groups (VCGs) showed that the genotypic diversity in G. zeae populations isolated from wheat in Argentina is high. The genetic structure of the G zeae populations characterized using AFLP markers showed that these populations are genetically and genotipically diverse and that there is a significant amount of genetic exchange occurring between genetically proximate populations. By a multiplex PCR assay of Tri3, Tri7 and Tri13, and chemical analysis the trichothecene genotype and chemotype of F. graminearum strains collected from three locations in Argentina were evaluated. Most strains (92%) had the 15-ADON genotype, with the remaining strains having the deoxynivalenol/nivalenol (DON/NIV) genotype. The strains with DON/NIV genotype produced DON when analyzed chemically. The accumulation of dexynivalenol (DON) in the grain is intimately related to the development of the disease in the field. Therefore, the current strategy to manage DON in cereals is to manage FHB. Biological control offers an additional strategy and can be used as part of an integrated management of FHB. ReferencesPalazzini, J.M, Ramirez, M.L., Alberione, E.J, Torres, A.M, Chulze, S:N (2009) Biological Control 51:370-376 Ramirez, M.L., Reynoso, M.M., Farnochi, M.C., Torres, A.M., Leslie, J.F., Chulze, S.N.(2007) Food Additives and Contaminants 24:1115-1120 Reynoso, M.M., Ramirez,M.L., Torres, A.M., Chulze, S.N (2011) Internacional Journal of Food Microbiology 145: 444-448.

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FUSARIUM DISEASES AND THEIR MYCOTOXINS IN MAIZE EARSG. P. Munkvold, Iowa State University Seed Science Center, Ames, IA, USA. E-mail: [email protected]

Maize produced in temperate regions of the world can be infected with a variety of Fusarium species, causing ear rot and other diseases. Ear rots caused by the F. graminearum complex, F. proliferatum, F. subglutinans, and F. verticillioides all can be economically important, and can result in mycotoxin contamination of grain. Fumonisins, deoxynivalenol and other trichothecenes, and zearalenone, are the most common, but other Fusarium toxins may be important. The crop production environment has a profound influence on the risk of mycotoxin contamination. Crop management practices influence the crop production environment and can be optimized to reduce mycotoxin risk. Pre-planting decisions including hybrid selection, planting date, crop rotation, tillage, fertilization, and planting density can influence infection and subsequent mycotoxin contamination; however, the importance of each management practice varies among mycotoxins and geographic areas. During the growing season, insect control is the most important practice affecting the risk of mycotoxin contamination. The most effective mycotoxin reductions are accomplished with transgenic insect resistance, but properly timed insecticide applications also can be effective. Irrigation should be optimized to prevent drought stress but also to avoid excessive moisture. Timely harvest is important because harvest delays can lead to increased mycotoxin development. Effective decisions about crop management during the season and post-harvest can be facilitated by the use of mycotoxin risk assessment or prediction models. As these models are refined and implemented more widely, management practices can be optimized, as part of a comprehensive mycotoxin risk management strategy that extends from pre-plant decision-making through crop utilization.

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FOOD INNOCUITY AND MYCOTOXINS: A VIEW FROM BRAZILL. H. Pfenning y L. R. Batista, Universidade Federal de Lavras, Lavras MG, Brazil. E-mail: [email protected], [email protected].

Production of mycotoxins in grains and fruits depends on several factors, some of them not subjected to control. The main factors are climate, crop management in the field, and procedures during harvest, processing and storing. Control of mycotoxin contamination of agricultural products in Brazil is a big challenge, due to the countrys continental dimensions, quite diverse climatic zones, and huge diversity of crops and agricultural derivates. Brazilian Government has recently published Law RDC n. 7 (Feb 2011), a complete and up-todate orientation about maximum limits of the most common toxins. This legislation is directed to beverages, foods and primary materials like cereals, nuts and fruits. Determination of toxin contents is based on recommendations given in the Codex Alimentarius, mainly by TLC and HPLC. The development of strategies to prevent contamination of grains, fruits and derivates during the whole production chain is based on the principles of Good Agricultural Practices (GAP) and concepts of HACCP - Hazard Analysis and Critical Control Points. To determine critical control points, one crucial step consists in the correct identification of potential mycotoxigenic species, mainly within the ascomycete genera Aspergillus, Penicillium and Fusarium. Knowledge of identity and distribution of main toxigenic species will allow for physiological and ecological studies on the influence of the substrate, microclimatic conditions, and fungal genotype in mycotoxin production levels and, in consequence, the proposal of specific strategies to reduce or even avoid contamination in particular crops. Detection and identification of toxigenic species is still based mainly on isolation procedures. Nevertheless, protocols for rapid and confident identification based on the PCR using specific primers are being developed. The development of techniques which permit monitoring of gene expression during toxin production could give a more precise picture of whether and when toxins are actually produced.

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Desjardins AE (2006) Fusarium Mycotoxins. Chemistry, Genetics and Biology. APS Press. St. Paul MN. Edwards SG, OCallaghan J, Dobson ADW (2002) PCR-based detection and quantification of mycotoxigenic fungi. Mycological Research 106: 1005-1025. (Review) Mortimore S, Wallace C 2003. HACCP. Food Industry Briefing Series. Blackwell Science. Oxford. Samson RA, Varga J (2007) Aspergillus systematics in the genomic era. Studies in Mycology, no. 59. CBS Utrecht.

References

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EL CONTROL BIOLGICO DE ENFERMEDADES, EN COMPARACIN CON EL DE MALEZAS Y DE PLAGAS ANIMALESR. Delhey. Dto. de Agronoma, Univ. Nac. del Sur, Baha Blanca, Buenos Aires. Correo-e: [email protected]

El Control Biolgico (CB) de enfermedades hasta la fecha ha sido menos exitoso que el de plagas s.s. y malezas. El anlisis de los diversos sistemas revela que hay diferencias esenciales entre los enfoques y mecanismos del CB de malezas y plagas s.s., por un lado, y el de patgenos, por el otro. En el primer caso, la actividad del agente de CB se dirige casi exclusivamente a la plaga s.l. la que es consumida (herbivora, parasitismo, patogenicidad). En el segundo, los agentes se dirigen tanto al patgeno como al cultivo a proteger, e incluso a factores ambientales, y los mecanismos son muy diversos, entre competencia, consumicin, secuestro de nutrientes, repelencia e induccin de resistencia. Se demuestra que el enfoque clsico (introduccin de un agente extico que, una vez establecido, se mantiene sin ms intervencin del hombre), tan exitoso en el CB de invasoras y plagas animales, slo en pocos casos sera viable en el CB de enfermedades. ste ltimo depender de enfoques menos contundentes y seguros, como inundacin y fomento, los que tambin son ms costosos para el productor. Se concluye que el CB de enfermedades nunca tendr la importancia que, el de plantas invasoras y plagas s.s.

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SITUAO E DESAFIOS PARA O BIOCONTROLE DE DOENAS DE PLANTAS NA AMRICA DO SULW. Bettiol, Embrapa Meio Ambiente, CP 6913820-000 Jaguarina, SP, Brasil. E-mail: [email protected]. Bolsista do CNPq.

A preocupao da sociedade com os impactos negativos da agricultura no ambiente e a contaminao da cadeia alimentar com pesticidas alterou o cenrio agrcola, resultando em mercados de alimentos produzidos sem o uso de pesticidas ou aqueles com selos que garantem que foram utilizados adequadamente. Esses aspectos esto fazendo com que a situao do uso dos pesticidas permeie a agenda ambiental dos pases da Amrica do Sul (AS). Dentre as possibilidades para a reduo do uso de pesticidas, o controle biolgico uma das mais discutidas, podendo tanto aproveitar o controle biolgico natural, quanto realizar a introduo massal de um agente de biocontrole. O estimulo ao controle biolgico natural ser na direo da utilizao de processos mais racionais preservando e estimulando o desenvolvimento de inimigos naturais. Para a introduo massal, h a necessidade de desenvolvimento de produtos contendo os agentes de biocontrole (ABC), de regulamentaes para o registro dos produtos e de polticas pblicas que estimulem o seu uso nos pases da AS. Nos ltimos anos, diversas biofbricas foram instaladas na AS, produzindo milhares de toneladas de biomassa de ABC, formando uma importante cadeia produtiva. Apesar disso, a maioria dos produtos comercializados no possui registro junto aos rgos competentes e no h poltica pblica que estimule o seu uso. Os mercados brasileiro e argentino de pesticidas foram de US$ 7,125 e US$ 2,164 bilhes; e os do Chile, Colmbia e Venezuela de US$ 476, US$ 350 e US$ 130 milhes em 2008. Nos demais pases da AS as vendas foram inferiores a US$ 100 milhes. De um modo geral, os ABC representam 1% do mercado, exceo feita Colmbia que em torno de US$ 20 milhes. No Brasil, apesar de ser o maior consumidor mundial de pesticidas, apenas 1% de ABC, portanto entre US$ 65-75 milhes. Entretanto, o crescimento desses produtos no mercado permite estimar que a comercializao de ABC atinja 5% do mercado nos prximos 10 anos, sendo os problemas de regulamentao e polticas pblicas os mais crticos. Em 2010, no Brasil tinha registrado 1339 pesticidas, sendo 18 base de ABC; no Chile 1519, sendo 30 base de ABC; na Argentina 3227, sendo 37


23 base de ABC; na Colmbia de 685 e 97 produtos base de ABC. A discrepncia nos nmeros est relacionada com a legislao. Enquanto na Argentina, Brasil e Chile a legislao para registro de agentes de biocontrole semelhante dos pesticidas, na Colmbia existe uma legislao especfica desde 2004 que dispe sobre o registro de produtos biolgicos, com reflexo marcante no nmero de produtos legalmente registrados. Nesses pases os produtos registrados para o controle de pragas so Bacillus thuringiensis, Metarhizium anisopliae, Beauveria bassiana, Lecanicillium lecanii, Paecilomices lilceos, Trichograma e Cotesia; e para o de doenas Trichoderma harzianum e Bacillus subtilis. Os problemas regulatrios e burocrticos so responsveis pelo aumento no nmero de produtos base de ABC ilegais na AS. Assim, os maiores desafios so: aprovao de uma legislao especfica para registro de ABC; reduo do tempo e dos custos necessrios para registro de ABC; isentar de registro os macro-organismos utilizados como ABC; e estabelecer o registro dos ABC considerando a praga ou doena alvo e no a cultura entre outros. Nesse sentido, as autoridades responsveis pelos aspectos relacionados com segurana sade pblica e ao ambiente tm alterado as regulamentaes nos ltimos anos para facilitar/estimular o registro de ABC. Diversos pases da AS tm trabalhado para o estabelecimento de uma legislao especfica para registro de ABC. No Brasil, foi aprovado em julho de 2009 um decreto que estabelece critrios para registro de ABC para agricultura orgnica. Esse decreto abre uma nova perspectiva para o mercado de controle biolgico. Tambm a criao da ABCBIO (Associao Brasileira das Empresas de Biocontrole) no Brasil estimulou o debate do tema e a melhoria dos produtos base de ABC. Associado aos aspectos regulatrios h a necessidade de que os pases da AS adotem polticas pblicas para estimular/favorecer o controle biolgico utilizando adequados instrumentos educacionais, legislativos, econmicos e financeiros semelhana do que ocorreu com o estimulo ao uso de pesticidas e fertilizantes. Essas medidas so necessrias para que o desenvolvimento tecnolgico busque a auto-sustentabilidade do sistema agrcola e no apenas caminhe para a sustentabilidade. Nesse sentido, uma agricultura auto-sustentvel deve manter a complexidade existente na natureza e no ser simplificada ao extremo como ocorreu no ltimo sculo, justamente o sculo responsvel por ultrapassar diversos limites planetrios e tendo a agricultura como uma das responsveis. 38

BIOCONTROL DE FITOPATGENOS EN CUBAM. Stefanova, Instituto de Investigaciones de Sanidad Vegetal, La Habana, Cuba. Correo-e: [email protected]

La necesidad de reducir el empleo de los plaguicidas qumicos por alternativas efectivas y amigables con el medio ambiente impuls la seleccin, el estudio de la naturaleza, el modo de accin y el desarrollo de bioproductos a partir de microorganismos promisorios, bacterias y hongos, para introducir el biocontrol, dentro del sistema de manejo de los fitopatgenos, como un mtodo eficaz. Productos a partir de cepas nativas de Trichoderma, se aplican bajo formas preventivas y dosis establecidas, contra especies de Phytophthora, Rhizoctonia, Pythium, Sclerotium y Fusarium en diversos cultivos, la combinacin con medidas agrotcnicas, fsicas y qumicas potencian la accin del hongo antagnico para una eficacia de un 80 % o ms. La introduccin del biocontrol a escalas tecnolgicas en tabaco y hortalizas contribuyo a la reduccin de perdidas de plntulas enraizadas en contenedores de 15 27 %. Los metabolitos, obtenidos mediante procedimiento biotecnolgico a partir de la bacteria Pseudomonas aeruginosa, cepa PSS (patente CI No. 1079/ 2002), muestran un efecto similar al de mancozeb contra Peronospora tabacina en tabaco y de Alternaria solani y Cladosporium fulvum en tomate en casas de cultivo. Los bioproductos HeberNem L, a base de la bacteria Tsukamurella paurometabola, cepa C-924, registrado en Cuba (# 001/ 2007) y en otros pases, de KlamiC, a partir de la cepa IMI SD 187 de Pochonia chlamydosporia, var. catenulata, y de Thurisave 25, de la cepa LBT25 de Bacillus thuringiensis son efectivos en el control de los nematodos del gnero Meloidogyne en organopnicos, cultivos protegidos y semiprotegidos, las premisas establecidas para su aplicacin conducen a una efectividad biolgica de un 70-80%. La participacin entusiasta y creativa del sector agrcola en todas sus formas de produccin, contribuye decisivamente al xito del biocontrol en Cuba.

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CONTROLE BIOLGICO NO BRASIL: NMEROS DE MERCADO E O POTENCIAL DE CRESCIMENTOD. Scacalossi Pedrazzoli. ABCBio (Associao Brasileira das Empresas de Controle Biolgico). E-mail: [email protected]

A demanda de insumos biolgicos no Brasil, em especial parasitides do gnero Trichogramma, aumenta a cada ano. Este aumento se deve, no s pela presso da sociedade em busca de alimentos mais saudveis e da preservao ambiental, com a exigncia da diminuio da utilizao de agroqumicos convencionais, mas, principalmente, devido eficincia no controle das pragas por agentes de controle biolgico produzidos em escala comercial. De acordo com a CPL Business Consultants (Wallingford, Oxsfordshire UK), somente o mercado de biopesticidas (microbiolgicos) no ano de 2009 foi de 400 milhes de dlares. O mercado mundial de macrobiolgicos continua ainda desconhecido e no Brasil estimado em 35 milhes de reais (US$19,8 milhes), liderados por parasitides na cultura da cana-de-acar. Os maiores desafios na comercializao deste tipo de organismo esto ligados tecnologia de produo e utilizao no campo. Seguindo os moldes de pases europeus e dos norteamericanos, comeam a aparecer as primeiras empresas comerciais do Brasil e da comeam os maiores problemas: produzir em larga escala, com qualidade e responsabilidade. Os problemas na prtica se devem, principalmente, ao aparecimento de empresas, que produzem organismos sem respaldo tcnico e sem a preocupao com a sua utilizao e eficincia. A regularizao do mercado por parte das empresas na forma de uma associao e o controle do governo, atravs do registro dos produtos, so fatores fundamentais para o crescimento da utilizao desta tecnologia. Fatores tambm fundamentais para o sucesso so, entre outros, a correta seleo de espcies e linhagens adaptadas s diferentes regies do pas, o controle de qualidade de agentes produzidos em laboratrio com o auxlio de Universidades e Institutos de Pesquisa, desenvolvimento e uso de tecnologia para transporte, liberao e avaliao da eficincia dos agentes de controle biolgico em campo. Os primeiros macrobiolgicos registrados no Brasil j comeam a aparecer, sinalizando uma mudana a mdio prazo do mercado de produtos biolgicos no Brasil. Esta mudana se deve ao fato das empresas 41


existentes no mercado estarem se adequando s leis federais e tambm pela entrada de empresas internacionais no mercado.

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BIOCONTROLADORES: PUEDE CONVIVIR EL PARADIGMA DEL CONTROL QUMICO CON EL PARADIGMA DEL CONTROL BIOLGICO?G. Gonzalez Anta, Rizobacter Argentina, UNNOBA. Correo-e:gganta@ rizobacter.com.ar

La respuesta a esa pregunta puede convivir el paradigma del control qumico con el paradigma del control biolgico?, es: SI. Los productos de sntesis qumica han realizado un aporte importante durante muchos aos al control de las enfermedades de semilla, de suelo y foliares de diferentes cultivos; pero este paradigma esta mutando lentamente hacia el empleo de herramientas microbiolgicas que puedan reemplazarlos en parte o totalmente. No hay duda que los biofungicidas son herramientas que permiten el control de patgenos y adems contienen valores aditivos como su capacidad de promover la generacin de factores de crecimiento y la mayor solubilizacin de nutrientes poco disponibles para las plantas. Afortunadamente se conocen las capacidades de biocontrol de numerosos microorganismos y sus metabolitos como Trichoderma sp, Bacillus sp, Streptomicetes sp, Pseudomonas sp, etc. y sus mecanismos de accin como mico parasitismo, antibiosis, competencia por nutrientes, resistencia inducida y/o inactivacin de enzimas de patgenos. Sin embargo, los centros de investigacin y la industria tienen que trabajar coordinadamente para que estos conocimientos cientficos y tcnicos se conviertan en tecnologa fcilmente adoptable por los tcnicos y productores a nivel de lote de produccin. Para ello, el desarrollo de formulaciones estables en el tiempo que aseguren una alta supervivencia y concentracin microbiana; la identificacin de microorganismos con amplio espectro de control de patgenos y la seleccin de biocontroladores compatibles con diferentes principios qumicos; permitirn desarrollar un conjunto de soluciones biolgicas, que reduzcan el impacto productivo de las enfermedades, mejoren el crecimiento y desarrollo de los cultivos, aseguren un mayor rendimiento y reduzcan significativamente el impacto ambiental. El nuevo paradigma del control biolgico como insumo tecnolgico en la agricultura, recin est comenzando a manifestarse, pero existe una impresionante reserva de microorganismos y sus metabolitos todava

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no estudiados que seguramente podrn ser empleados como nuevas herramientas de biocontrol.

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DIAGNOSTIC NETWORKS THE ROLE OF THE ADVISORS. A. Miller, The Ohio State University, Ohio Agricultural Research and Development Center, Wooster, Ohio USA. E-mail: [email protected]

Plant disease diagnostic networks serve important roles in both plant safeguarding and disease management decision-making. The effectiveness of such networks is directly related to the quality of the expertise of their members. The ability to be an expert diagnostician for any given crop requires a strong background in plant pathology and understanding of plant pathogens, and years of direct experience in the laboratory and field. Any one individual is unlikely to be an expert in all diseases and pathogens and all diagnostic technology platforms. A well-functioning diagnostic laboratory includes persons adept at microbiological analyses including culturing, serological and molecular assays, and microscopy. However, the diagnostic laboratory must reach into the farming community to offer its services where they are needed. This is best accomplished through an established Extension system, with good communication and knowledge sharing from crop specialist to laboratory diagnostician to local Extension personnel, on to advanced laypersons such as Master Gardeners and experienced farmers. The latter three groups (Extension personnel, Master Gardeners, farmers) are likely the first to encounter a new disease/invasive species, and can be trained as first responders. First responder training provides standard procedures for reporting and sample submission to maximize the speed and efficiency of identifying critical pathogens. First responder training results in an amplification of the advisory capacity of the specialist by extending his or her eyes and ears well into the community of farmers and gardeners. We have seen a significant increase in the submission of digital images by farmers and Master Gardeners in lieu of submission of a physical sample to our diagnostic lab. While not all diseases are amenable to diagnosis via a digital image, this approach also extends the reach of the specialist (advisor) to a larger group of clientele.

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IDENTIFICACIN DE ENFERMEDADES: ROL DEL PROFESIONAL DE LA AGRONOMA Y DE LOS LABORATORIOS DE ANLISISA. Escande, EEA Balcarce-INTA y Facultad de Ciencias Agrarias-UNMdP RN 226 Km. 73,5; CC 276, B7620BKL Balcarce, Argentina. Correo-e:aescande@ balcarce.inta.gov.ar

El conocimiento de la causa del problema o enfermedad es fundamental para decidir la estrategia de manejo de la sanidad en los cultivos agropecuarios. Por eso se considera necesario incrementar la participacin en el diagnstico de todos los actores involucrados en los cultivos, especialmente aquellos que estn en contacto directo con dichos cultivos, y el desarrollo de laboratorios de anlisis especiales. El campo brinda claves que ayudan al diagnstico tales como la distribucin del problema en el cultivo, la importancia relativa del problema en el lote, las especies afectadas (cultivadas o espontneas), la historia sanitaria del lote; o las condiciones previas a la aparicin del problema. Los objetivos de esta estrategia incluyen: i) Identificar al profesional responsable del cultivo y al extensionista como actores claves para el diagnstico de fitoenfermedades; ii) Actualizar al profesional responsable del cultivo y al extensionista en el reconocimiento de los principales problemas de sus cultivos segn zona de produccin; iii) Promover la formacin del profesional responsable del cultivo y al extensionista y otorgarles la correspondiente certificacin de especialista en clnica de campo de cultivos especficos; iv) Desarrollar claves para determinacin de enfermedades por cultivo y estado fenolgico del cultivo; v) Optimizar el uso de la informacin que nos da el campo; vi) Promover la especializacin y certificacin de laboratorios de anlisis fitopatolgicos en cultivos especficos o anlisis especiales; vii) Preparar a estudiantes de fitopatologa en anlisis fitopatolgicos especficos; viii) Promover que el profesional responsable del cultivo y el extensionista soliciten anlisis de laboratorio. El mayor nivel de conocimiento del cultivo por parte de los profesionales a cargo orientar la solicitud de anlisis especficos. La complementacin de conocimientos de campo y de anlisis de laboratorio especficos posibilitar un trabajo en red que mejorar la certeza y eficiencia del diagnstico. 47


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RED NACIONAL DE PROTECCIN VEGETAL (RedNPV)V. C. Conci12; J. Imwinkelried3; R. Lpez4 y D. A. Ducasse1.1 INTA-IFFIVE Cno 60 cuadras km 5,5 (5119) Crdoba., 2 CONICET, 3 INTA EEA Manfredi Ruta Nac. 9 km 636, Manfredi, Crdoba, 4 INTA EEA. Bordenave, Ruta Pcial. 76 km. 36.5 (8187) Bordenave. Bs As, Argentina. Correo-e: [email protected]. gov.ar

La RedNPV agrupa capacidades cientfico-tecnolgicas en Proteccin Vegetal pertenecientes a diferentes instituciones nacionales pblicas y privadas, y promueve su articulacin para atender la prevencin y el manejo de organismos perjudiciales para la agricultura. Pone a disposicin de los usuarios una base de datos que facilita la comunicacin entre investigadores y laboratorios de las disciplinas fitopatologa, entomologa y disherbologa pertenecientes al INTA, Universidades pblicas y privadas; diferentes organismos de legislacin; laboratorios de servicios, institutos y centros nacionales y provinciales; estatales y privados. A travs de su sito Web www. rednpv.org.ar permite la bsqueda de investigadores y laboratorios vinculados a la proteccin vegetal, equipamiento disponible, tcnicas utilizadas, as como colecciones de organismos perjudiciales y benficos. Incluye adems, las publicaciones realizadas por ellos, los proyectos que estn desarrollando y un espacio para anunciar cursos, reuniones, publicaciones de libros, etc. La informacin disponible es la que cada investigador carga en el sitio Web. La RedNPV cuenta con 503 investigadores y 37 laboratorios inscriptos. Cada profesional, laboratorio o grupo de investigacin, figura con su especialidad, rea de aplicacin, trabajos, publicaciones y el modo ms eficaz para contactarlo, telfonos, correo electrnico, lugar de trabajo y direccin. El sitio Web de la RedNPV es un espacio libre, abierto y creado para generar vnculos, para aportar y buscar soluciones en beneficio del la comunidad cientfica y la produccin nacional.Financiamiento: INTA

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CUANDO LA RED NOS CONTIENEC. Maneiro, EEA Balcarce-INTA, y Facultad de Ciencias Agrarias-UNMdP RN 226, Km. 73,5; CC 276, B7620BKL Balcarce, Argentina. Correo-e: [email protected]

Un extensionista es en general un profesional denominado generalista, dada la cantidad de conocimientos que debe poner en prctica en cada resolucin que toma ante un problema, cuando este se presenta, en condiciones de campo. Enfermedades, plagas, malezas, fertilidad de suelos, aspectos fisiolgicos, inclemencias climticas, son parte de los conocimientos, que se ponen en juego ante la aparicin de signos que indican anomalas de un cultivo. En algunos de los aspectos mencionados, la propia experiencia o lo obvio del signo, permiten determinar con certeza el problema, pero hay aspectos que se tornan ms difciles, ante lo confuso de los sntomas. Entonces, se requiere del ojo experto de un especialista. Este es el caso particular de las enfermedades y sus agentes causales. Se hace muy difcil, salvo muy buena formacin previa, diagnosticar con adecuada certeza, en condiciones de campo, determinadas enfermedades, en particular cuando se las observa por primera vez. En este caso se necesita de la ayuda de un experto. Hace pocos aos atrs, la demora en conseguir esa opinin, debido a las distancias y los ineficientes medios de comunicacin, podan ser causa de prdidas irreparables en los cultivos. Hoy, los avances en medios de comunicacin, telfonos celulares, Internet, cmaras digitales, etc., permiten mejorar sensiblemente esta situacin. Perolos referentes a consultar donde estn ?. A veces a distancias considerables, o no se los encuentra cuando ms los necesitamos. Esta situacin se puede revertir a travs de un fuerte trabajo integrado entre los profesionales de campo, los referentes especialistas y los laboratorios pblicos y privados. Cada uno desde su lugar de trabajo y manteniendo su rol, puede aportar para que este tipo de situaciones dejen de ser un inconveniente de riesgo para la empresa agropecuaria. Adems el trabajo integrado favorece a todas las partes. Mejora las capacidades de todos, favorece el intercambio de conocimientos, incrementa la a cantidad de casos en estudio y permite visualizar la distribucin geogrfica del problema. 51


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REDES DE DIAGNOSTICO, ROL DEL ASESOR O EXTENSIONIESTAM. Redolatti, Ingeniero Agrnomo, Asesor grupos CREA Tandil y San Manuel. Tandil, Argentina. Correo-e: [email protected]

El asesor tcnico agrcola cumple distintos roles dentro de las Redes de diagnstico de enfermedades interactuando con los productores, los equipos de investigacin y las compaas que proveen productos curativos y/o preventivos. Los tcnicos estn capacitados para diagnosticar patologas y recomendar prcticas de control para la mayora de las enfermedades de aparicin ms frecuentes. Evitando, de esta forma, que los centros de investigacin se vean sobrepasados con determinaciones de baja relevancia y complejidad. Otra de las funciones del asesor es la de hacer de nexos entre la produccin y los centros de investigacin. En esta tarea, los asesores tcnicos tienen la fortaleza de conocer en detalle el sistema productivo donde se desarrolla la patologa y conocer la historia del lote donde tuvo lugar. Esto permite hacer un seguimiento en el tiempo de la patologa y de las condiciones ambientales en las que se produce. En muchos casos, son los asesores tcnicos quienes muestran a los investigadores las nuevas enfermedades o problemticas. Por ltimo, sin duda alguna, la funcin ms importante de los asesores tcnicos es planificar teniendo en cuenta la historia de los lotes, el perfil sanitario de las variedades o hbridos, la influencia de la fecha de siembra, densidad, humedad del suelo, cantidad de rastrojo, posicin topogrfica, fertilidad del lote, productos utilizados y otros factores que predisponen en forma diferente a la aparicin y virulencia de las enfermedades. Y as, desarrollar sistemas de produccin que sean econmicamente rentables y que minimicen el riesgo de que los patgenos comprometan la rentabilidad y productividad de los cultivos. Para esta tarea, es de suma importancia estar bien informados de todos los avances que se van generando en los centros de investigacin pblicos y privados relacionados con la produccin agrcola lo cual se logra fortaleciendo los vnculos entre todos los integrantes de las Redes de diagnstico.

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PARTICIPACIN Y RESPONSABILIDAD DEL SECTOR PRIVADO EN LA OBTENCIN DE UNA MIRADA SISTMICA A LA SALUD DE LOS CULTIVOS: LA EXPERIENCIA DE UNA EMPRESA PRIVADA EN EL DIAGNSTICO DE ENFERMEDADES DE LA SEMILLA DE PAPAA. M. Escarr, Diagnsticos Vegetales S.A., Mjico 2446,7600 Mar del Plata, Argentina. Correo-e: [email protected]

Los profesionales de la agronoma que hemos vivido y tenido participacin en la extraordinaria evolucin del sector agroindustrial de la papa en Argentina de los ltimos 25 aos, comprendimos que se requiere una mirada sistmica en el desarrollo de conocimientos para aumentar la productividad y para mejorar la sustentabilidad, en congruencia con el medio ambiente. La actividad del sector privado en sus roles de asesor en el manejo sanitario de los cultivos de prestador servicios de diagnstico es realizada como un participante activo y constitutivo del mismo, aportando a las redes de diagnostico fitosanitario, informacin desde la fuente y panormica acerca de las realidades emergentes, fortaleciendo las estrategias para el control integrado de enfermedades del cultivo de papa. La oferta desde el sector privado en el control de sanidad de semillas de papa por tcnicas que, confiables y rpidas en la informacin para tomar decisiones, tuvo rpida aceptacin por parte de los sectores de la produccin y de usuarios de semillas de papas de la Argentina; al mismo tiempo, desde las instituciones del estado, se correspondi con un rpido reconocimiento mediante la regulacin de esta actividad y se estableci una estrecha colaboracin privado-estatal para el control de la sanidad de las semillas en proceso de fiscalizacin y favoreci el rpido desarrollo de conocimientos acerca de la distribucin de los patgenos que afectan al cultivo, de variabilidad de los patgenos y de las respuestas de las variedades vegetales, de las condiciones que afectan su difusin, de su impacto en la economa del sector.

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PANELES PANORAMA FITOPATOLOGICO DE AJO Y CEBOLLA Nuevos desafos para la problemtica de postcosecha en cebolla, en el sur argentino. Mirta Kiehr..

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Situacin actual y amenaza a futuro de virus en cebolla y ajo. Vilma C. Conci .............. 61 Una resea de los estudios de Phoma terrestris hansen en Argentina. Jorge G. Lafi y C. E. Linardelli.. 63 SITUACIN ACTUAL DEL COMPLEJO VIRAL DE LA PESTE NEGRA EN HORTCOLAS Agentes causales: descripcin, distribucin, mtodos de deteccin o diagnstico. Paola M. Lpez Lambertini .. 65 Epidemiologa de enfermedades causadas por tospovirus: consideraciones sobre el manejo y el uso de la resistencia. Elena Dal B ... 67 Relacin vector-virus: manejo de vectores. Carlos M. De Borbn..

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ENFERMEDADES CUARENTENARIAS Comercio mundial de vegetales y proteccin cuarentenaria. M. Fernanda Wagner...

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Enfermedad del sharka: etiologa, epidemiologa, situacin actual en Argentina. Diana B. Marini... 73 Fuego bacteriano: etiologa, epidemiologa. probabilidad de la introduccin, dispersin y radicacin del patgeno en Argentina. Mirta Rossini..

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NUEVOS DESAFOS PARA LA PROBLEMTICA DE POSTCOSECHA EN CEBOLLA, EN EL SUR ARGENTINOM. Kiehr, Dto de Agronoma, U N del Sur, Baha Blanca, Buenos Aires, Argentina. Correo-e: [email protected]

En el pasado, podredumbres blandas causadas por bacterias y hongos, han jugado un papel secundario en la regin cebollera sur, salvo en temporadas muy lluviosas. En los ltimos aos este tipo de podredumbres ha ido aumentando y en la temporada 2009-10 se transform en el problema dominante. Se adjudica este incremento a cambios en el sistema de siembra y riego (platabanda de 12 hileras en lugar de los tradicionales camellones a cuatro hileras), lo que aumentara el riesgo de anegamientos; a esto se suman lluvias inoportunas en el perodo de cosecha, en 2010. En la misma temporada se observ adems una intensidad inusualmente baja de carbonilla (Aspergillus niger). En una actividad conjunta (CORFO Ro Colorado, Funbapa, INTA, UNSur, productores) se realiz un monitoreo y encuesta a productores y se iniciaron estudios etiolgicos. Se muestrearon 97 lotes tomando 200 bulbos/lote. En 94 muestras (prevalencia 97 %) se encontraron podredumbres blandas, con una incidencia media de 11,5 % y un valor mximo de 42 %. El anlisis de la encuesta revel que la incidencia est correlacionada en primer lugar con el manejo del agua. Se aislaron bacterias y Fusarium spp., y con las primeras se realizaron pruebas de patogenicidad en bulbos sanos. Se iniciaron estudios de identificacin de los agentes de pudricin.

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SITUACIN ACTUAL Y AMENAZA A FUTURO DE VIRUS EN CEBOLLA Y AJOV. C. Conci, INTA-IFFIVE y CONICET, Camino 60 cuadras km 5,5, X5020ICA Crdoba, Argentina. Correo-e: [email protected]

En Alliaceae se han citado numerosos virus responsables de importantes daos en el cultivo y prdidas en la produccin. En ajo debido a la exclusiva propagacin agmica de esta especie los virus se acumulan en la planta formando un complejo integrado por unas 10 especies diferentes pertenecientes principalmente a los gneros Potyvirus, Carlavirus y Allexivirus. Ellos causan prdidas en los rendimientos que llegan hasta un 60% de disminucin del peso de los bulbos ocasionando cuantiosas mermas en la economa nacional ya que el ajo es la principal hortaliza exportable del pas. No existe naturalmente ajo libre de virus, pero se ha logrado la produccin de plantas de plantas sanas a travs del cultivo de meristema. Este material es multiplicado en forma controlada y luego utilizado por los productores para obtener mejores rendimientos. Para ello es necesaria la produccin y reposicin permanente de ajos libres de virus ya que en el campo las plantas se vuelven a infectar. En cebolla el panorama es diferente debido a que esta especie se multiplica por semilla y entonces los virus que no se transmites por esta va son eliminados en esta etapa del ciclo de cultivo. Sin embargo, este cultivo es amenazado por algunos virus que son capaces de producir importantes prdidas durante la produccin. Originalmente el virus mas importante en cebolla era el Onion Yellow Dwarf Virus aunque su importancia se ha visto disminuida probablemente por el uso de cultivares resistentes. Actualmente la mayor amenaza la constituye el Iris Yellow Spot Virus (IYSV). Este virus ha sido citado como responsable de prdidas de hasta un 100% en Brasil y en el noroeste de Estados Unidos. El IYSV recientemente fue detectado en Argentina aunque todava desconocemos su incidencia.

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UNA RESEA DE LOS ESTUDIOS DE Phoma terrestris EN ARGENTINAJ. G. Lafi y C. E. Linardelli, Universidad Nacional de Cuyo, Facultad de Ciencias Agrarias, Ctedra de Fitopatologa. Mendoza, Argentina. Correo-e: [email protected]

La Raz rosada de la cebolla es causada por el hongo mitosprico de suelo Phoma terrestris Hansen y est distribuida mundialmente en todas las reas cebolleras. En Argentina presenta carcter endmico y su desarrollo se ve favorecido, principalmente, en las zonas de cultivo del centro-oeste y norte del pas. Hasta el momento, no hay un medio qumico y/o fsico que sea eficiente y econmicamente rentable a nivel comercial para el control de este patgeno, por lo que es necesaria la obtencin de variedades resistentes. Si bien existen cultivares importadas resistentes a la enfermedad, en Argentina han manifestado susceptibilidad. Una hiptesis probable es que los aislados argentinos del patgeno presentan diferencias con los que afectan al cultivo en el hemisferio norte. Para probar esta hiptesis, se ha obtenido una coleccin de P. terrestris conformada por aislados de las zonas argentinas mencionadas y por aislados del hemisferio norte. En los ltimos aos, se ha evaluado la diversidad de la coleccin a nivel morfolgico, a travs de marcadores fenotpicos observados in-vitro en las colonias; a nivel fisiolgico, mediante el estudio del crecimiento a diferentes valores de temperatura y de pH; a nivel patognico, a travs de pruebas de patogenicidad bajo condiciones controladas utilizando la cv. Valcatorce; y a nivel molecular, mediante el empleo de RAPDs. Se han caracterizado las zonas cebolleras argentinas en base a estas variabilidades y se han comparado los aislados argentinos con los forneos. Los resultados indican que los aislados argentinos difieren de los extranjeros en todos los rasgos estudiados y que existe variabilidad del patgeno entre y dentro de las zonas argentinas de produccin de cebolla.Financia: SECTyP UNCUYO e INTA.

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SITUACIN ACTUAL DEL COMPLEJO VIRAL DE LA PESTE NEGRA EN HORTCOLAS. AGENTES CAUSALES: DESCRIPCIN, DISTRIBUCIN, MTODOS DE DETECCIN O DIAGNSTICOP. M. Lpez Lambertini, IFFIVE-INTA, Crdoba, Argentina. Correo-e: [email protected]

El gnero Tospovirus agrupa a los virus de plantas que se transmiten por trips (Thysanoptera, Thripidae) dentro de la familia Bunyaviridae. Son patgenos de importancia econmica debido a las prdidas que ocasionan en cultivos como tomate, pimiento, papa, tabaco, cebolla y ornamentales. Presenta un genoma constituido por tres ARNs de codificacin negativa que se encuentran asociados a la protena N para formar una ribonuleoprotena empaquetada por una membrana lipdica. Como primer paso para el desarrollo de estrategias de manejo basadas en la utilizacin de resistencia es necesario conocer la diversidad gentica y distribucin de los tospovirus en Argentina. En nuestro pas se han identificado cinco especies virales: Tomato Spotted Wilt Virus (TSWV), Tomato Chlorotic Spot Virus (TCSV), Groundnut Ring Spot Virus (GRSV) y recientemente Impatiens Necrotic Spot Virus (INSV) e Iris Yellow Spot Virus (IYSV). El GRSV esta ampliando su rango de hospedantes en Argentina pudiendo destacarse entre otros nuevos hospedantes a la soja por su potencial impacto epidmico. En papa se ha convertido en una limitante sanitaria con un distribucin diferencial de especies; el GRSV en la regin central del pas y el TSWV en Buenos Aires. El IYSV fue detectado por primera vez en Argentina en 2010 en cebolla de verdeo en Crdoba y en Baha Blanca. Las especies de tospovirus pueden ser confundidas entre s debido a que presentan sntomas similares, infectan hospedantes en comn, se transmiten por las mismas especies de trips y algunas de ellas poseen reaccin serolgica cruzada. El desarrollo de alternativas de diagnstico especficas y sensibles como DAS-ELISA, IC-RTPCR, Multiplex RT-PCR, Print RT-PCR, PCR anidado y real time RTPCR ofrecen en muchos casos soluciones para la deteccin de este complejo grupo de patgenos virales.

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EPIDEMIOLOGA DE ENFERMEDADES CAUSADAS POR TOSPOVIRUS. CONSIDERACIONES SOBRE EL MANEJO Y EL USO DE LA RESISTENCIAE. Dal B , Centro de Investigaciones en Fitopatologa. Facultad de Ciencias Agrarias y Forestales. UNLP. 60 y 119, 1900 - La Plata, Argentina. Correo-e: [email protected]

Los Tospovirus tienen caractersticas epidemiolgicas que, por un lado hacen posible la ocurrencia de grandes epidemias, y por el otro desafan las estrategias diseadas para su manejo. 1) Son virus extremadamente polfagos (infectan a Mono y Dicotiledneas). Esto le permite al inculo permanecer en el ambiente en ausencia de situaciones climticas extremas. Afecta cultivos y malezas, y lo hace en todas las estaciones del ao en climas templados, por lo que la superposicin de cultivos susceptibles, algunos de ellos de ciclos cortos, preserva las fuentes de inculo. 2) sor transmitidos con mucha eficiencia por algunas especies de trips, por lo que la epidemiologa del virus se halla intrincadamente ligada con la del vector. 3) si bien no se transmite por semillas, infecta especies que se multiplican y atraviesan lmites y fronteras como esquejes, hijuelos, plantines, injertos, etc. 4) Todava no estn bien aclaradas las diferencias epidemiolgicas entre las distintas especies de Tospovirus. Todo esto, junto con las caractersticas de los vectores, contribuye a que la cantidad de inculo producido por estos virus en un ambiente pueda recuperarse con facilidad luego de haber decrecido. Dentro de las estrategias de manejo, estn las que tratan de impedir la dispersin de inculo a partir de 1)eliminacin de sus fuentes: plantas o cultivos abandonados, plantas cultivadas y malezas dentro y fuera del cultivo, otros cultivos, 2) control sanitario de plantines o partes vegetales para multiplicacin y produccin 3) limitar la poblacin y actividad de trips, 4) elementos de alarma o prediccin 5) uso de variedades resistentes o tolerantes en ausencia de las primeras, aunque no existen para todos los cultivos. En relacin a este ltimo punto, slo existen variedades de pimiento y tomate resistentes a TSWV. En cada uno de ellos la resistencia es conferida por un nico gen, proveniente de

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un antecesor de la especie1. No est bien develada la forma en que confieren esta resistencia. Sin embargo hay aislamientos que pueden romperla, como ha ocurrido con cultivares resistentes de pimiento en Argentina2 y de pimiento y tomate en pases de Europa3. Si bien esto trae serias consecuencias en aos de alta concentracin de inculo y de alta poblacin de vectores, cabe inferir que una variedad resistente tendr mejor comportamiento que una susceptible en las mismas condiciones epidemiolgicas.

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Roggero P. 2002. Infection of Tospoviruses in Pepper And Control by Resistant

Plants. Biolgico, So Paulo, v.64, n.2, p.179-181, jul./dez. Calvo L., Ronco L., Rolln C. Balatti P. y Dal B E.. 2008 Virosis de Pimiento en La Plata. 1er Congreso Argentino de Fitopatologa, 28 al 30 de mayo Crdoba. 3 Roggero, P.; Masenga, V.; Tavella, L. Field isolates of Tomatospotted wilt virus overcoming resistance in pepper and their sp

2011_primeras Experiencias Control Sarna Pecan MISIONES

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